In this article, we report the results of a 4-dimensional (3 spatial dimensions plus time) in-situ creep experiment on a milli-core shale plug from Barnett formation in Texas. An outstanding challenge in shale mechanics is connecting observable characteristics to predictable mechanical and hydraulic behavior. We employ novel imaging and analysis techniques to statistically link sample mineralogy and structure to observed deformation. In particular, we focus on mechanisms of porosity reduction during transient response to step changes in stress, analogous to the aseismic deformation that occurs after an episode of fracturing. Our main goal in this study is to take the first steps to visualize and capture the small-scale deformation mechanisms involved in creep of shales, using imaging techniques. To do so, we conducted a uniaxial creep experiment inside an Xradia Versa 520 micro-CT system for 12 h at room temperature under a constant uniaxial stress of 25 MPa. We employed a Digital Volume Correlation (DVC) method to measure micro-scale deforspmation of the sample by comparing the resulting volumetric images with a high-resolution scan of the sample obtained prior to the creep experiment. The results indicate that the time-dependent deformation in the compliant clay plus kerogen matrix constituents facilitates rigid grain rotation and compaction of intergranular porosity at the boundary between rigid grains and matrix.

在本文中，我们报告了对德克萨斯州 Barnett 地层的毫核页岩塞进行的 4 维（3 个空间维度加时间）原位蠕变实验的结果。页岩力学的一个突出挑战是将可观察的特征与可预测的机械和水力行为联系起来。我们采用新颖的成像和分析技术将样品矿物学和结构与观察到的变形进行统计联系。特别是，我们关注在应力阶跃变化的瞬态响应过程中孔隙率降低的机制，类似于压裂后发生的抗震变形。我们在这项研究中的主要目标是采取第一步，使用成像技术可视化和捕获页岩蠕变中涉及的小规模变形机制。为此，我们在 Xradia Versa 520 微型 CT 系统内在室温下在 25 MPa 的恒定单轴应力下进行了 12 小时的单轴蠕变实验。我们采用数字体积相关 (DVC) 方法通过将所得体积图像与蠕变实验之前获得的样品的高分辨率扫描进行比较来测量样品的微尺度变形。结果表明，柔顺粘土和干酪根基质成分中的时间相关变形促进了刚性颗粒旋转和刚性颗粒和基质之间边界处粒间孔隙的压实。我们采用数字体积相关 (DVC) 方法通过将所得体积图像与蠕变实验之前获得的样品的高分辨率扫描进行比较来测量样品的微尺度变形。结果表明，柔顺粘土和干酪根基质成分中的时间相关变形促进了刚性颗粒旋转和刚性颗粒和基质之间边界处粒间孔隙的压实。我们采用数字体积相关 (DVC) 方法通过将所得体积图像与蠕变实验之前获得的样品的高分辨率扫描进行比较来测量样品的微尺度变形。结果表明，柔顺粘土和干酪根基质成分中的时间相关变形促进了刚性颗粒旋转和刚性颗粒和基质之间边界处粒间孔隙的压实。